Commit Graph

31 Commits

Author SHA1 Message Date
Jakub Kicinski
2d91ecace6 strparser: pad sk_skb_cb to avoid straddling cachelines
sk_skb_cb lives within skb->cb[]. skb->cb[] straddles
2 cache lines, each containing 24B of data.
The first cache line does not contain much interesting
information for users of strparser, so pad things a little.
Previously strp_msg->full_len would live in the first cache
line and strp_msg->offset in the second.

We need to reorder the 8 byte temp_reg with struct tls_msg
to prevent a 4B hole which would push the struct over 48B.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-07-08 18:38:44 -07:00
John Fastabend
e0dc3b93bd bpf: sockmap, strparser, and tls are reusing qdisc_skb_cb and colliding
Strparser is reusing the qdisc_skb_cb struct to stash the skb message handling
progress, e.g. offset and length of the skb. First this is poorly named and
inherits a struct from qdisc that doesn't reflect the actual usage of cb[] at
this layer.

But, more importantly strparser is using the following to access its metadata.

  (struct _strp_msg *)((void *)skb->cb + offsetof(struct qdisc_skb_cb, data))

Where _strp_msg is defined as:

  struct _strp_msg {
        struct strp_msg            strp;                 /*     0     8 */
        int                        accum_len;            /*     8     4 */

        /* size: 12, cachelines: 1, members: 2 */
        /* last cacheline: 12 bytes */
  };

So we use 12 bytes of ->data[] in struct. However in BPF code running parser
and verdict the user has read capabilities into the data[] array as well. Its
not too problematic, but we should not be exposing internal state to BPF
program. If its really needed then we can use the probe_read() APIs which allow
reading kernel memory. And I don't believe cb[] layer poses any API breakage by
moving this around because programs can't depend on cb[] across layers.

In order to fix another issue with a ctx rewrite we need to stash a temp
variable somewhere. To make this work cleanly this patch builds a cb struct
for sk_skb types called sk_skb_cb struct. Then we can use this consistently
in the strparser, sockmap space. Additionally we can start allowing ->cb[]
write access after this.

Fixes: 604326b41a ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jussi Maki <joamaki@gmail.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/20211103204736.248403-5-john.fastabend@gmail.com
2021-11-09 01:05:28 +01:00
Alexander Aring
e3ae2365ef net: sock: introduce sk_error_report
This patch introduces a function wrapper to call the sk_error_report
callback. That will prepare to add additional handling whenever
sk_error_report is called, for example to trace socket errors.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-06-29 11:28:21 -07:00
David S. Miller
92ad6325cb Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Minor SPDX change conflict.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-06-22 08:59:24 -04:00
Thomas Gleixner
d2912cb15b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:55 +02:00
Jakub Kicinski
da29e4b466 net/tls: fully initialize the msg wrapper skb
If strparser gets cornered into starting a new message from
an sk_buff which already has frags, it will allocate a new
skb to become the "wrapper" around the fragments of the
message.

This new skb does not inherit any metadata fields.  In case
of TLS offload this may lead to unnecessarily re-encrypting
the message, as skb->decrypted is not set for the wrapper skb.

Try to be conservative and copy all fields of old skb
strparser's user may reasonably need.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-06-04 14:33:50 -07:00
Paul Gortmaker
15253b4a71 net: strparser: make it explicitly non-modular
The Kconfig currently controlling compilation of this code is:

net/strparser/Kconfig:config STREAM_PARSER
net/strparser/Kconfig:  def_bool n

...meaning that it currently is not being built as a module by anyone.

Lets remove the modular code that is essentially orphaned, so that
when reading the driver there is no doubt it is builtin-only.

Since module_init translates to device_initcall in the non-modular
case, the init ordering remains unchanged with this commit.  For
clarity, we change the fcn name mod_init to dev_init at the same time.

We replace module.h with init.h and export.h ; the latter since this
file exports some syms.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-22 21:50:54 -07:00
David S. Miller
6b0a7f84ea Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflict resolution of af_smc.c from Stephen Rothwell.

Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-17 11:26:25 -07:00
Jakub Kicinski
93e2125477 net: strparser: fix comment
Fix comment.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-10 14:12:45 -07:00
Jakub Kicinski
4a9c2e3746 net: strparser: partially revert "strparser: Call skb_unclone conditionally"
This reverts the first part of commit 4e485d06bb ("strparser: Call
skb_unclone conditionally").  To build a message with multiple
fragments we need our own root of frag_list.  We can't simply
use the frag_list of orig_skb, because it will lead to linking
all orig_skbs together creating very long frag chains, and causing
stack overflow on kfree_skb() (which is called recursively on
the frag_lists).

BUG: stack guard page was hit at 00000000d40fad41 (stack is 0000000029dde9f4..000000008cce03d5)
kernel stack overflow (double-fault): 0000 [#1] PREEMPT SMP
RIP: 0010:free_one_page+0x2b/0x490

Call Trace:
  __free_pages_ok+0x143/0x2c0
  skb_release_data+0x8e/0x140
  ? skb_release_data+0xad/0x140
  kfree_skb+0x32/0xb0

  [...]

  skb_release_data+0xad/0x140
  ? skb_release_data+0xad/0x140
  kfree_skb+0x32/0xb0
  skb_release_data+0xad/0x140
  ? skb_release_data+0xad/0x140
  kfree_skb+0x32/0xb0
  skb_release_data+0xad/0x140
  ? skb_release_data+0xad/0x140
  kfree_skb+0x32/0xb0
  skb_release_data+0xad/0x140
  ? skb_release_data+0xad/0x140
  kfree_skb+0x32/0xb0
  skb_release_data+0xad/0x140
  __kfree_skb+0xe/0x20
  tcp_disconnect+0xd6/0x4d0
  tcp_close+0xf4/0x430
  ? tcp_check_oom+0xf0/0xf0
  tls_sk_proto_close+0xe4/0x1e0 [tls]
  inet_release+0x36/0x60
  __sock_release+0x37/0xa0
  sock_close+0x11/0x20
  __fput+0xa2/0x1d0
  task_work_run+0x89/0xb0
  exit_to_usermode_loop+0x9a/0xa0
  do_syscall_64+0xc0/0xf0
  entry_SYSCALL_64_after_hwframe+0x44/0xa9

Let's leave the second unclone conditional, as I'm not entirely
sure what is its purpose :)

Fixes: 4e485d06bb ("strparser: Call skb_unclone conditionally")
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-04-10 13:07:02 -07:00
Kangjie Lu
228cd2dba2 net: strparser: fix a missing check for create_singlethread_workqueue
In case create_singlethread_workqueue fails, the check returns
an error to callers to avoid potential NULL pointer dereferences.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-15 12:51:56 -07:00
YueHaibing
bd707f17ef strparser: remove redundant variable 'rd_desc'
Variable 'rd_desc' is being assigned but never used,
so can be removed.

fix this clang warning:
net/strparser/strparser.c:411:20: warning: variable ‘rd_desc’ set but not used [-Wunused-but-set-variable]

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-08-01 10:00:06 -07:00
David S. Miller
5cd3da4ba2 Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net
Simple overlapping changes in stmmac driver.

Adjust skb_gro_flush_final_remcsum function signature to make GRO list
changes in net-next, as per Stephen Rothwell's example merge
resolution.

Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-03 10:29:26 +09:00
Vakul Garg
4e485d06bb strparser: Call skb_unclone conditionally
Calling skb_unclone() is expensive as it triggers a memcpy operation.
Instead of calling skb_unclone() unconditionally, call it only when skb
has a shared frag_list. This improves tls rx throughout significantly.

Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Suggested-by: Boris Pismenny <borisp@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-30 21:25:39 +09:00
Doron Roberts-Kedes
977c7114eb strparser: Remove early eaten to fix full tcp receive buffer stall
On receving an incomplete message, the existing code stores the
remaining length of the cloned skb in the early_eaten field instead of
incrementing the value returned by __strp_recv. This defers invocation
of sock_rfree for the current skb until the next invocation of
__strp_recv, which returns early_eaten if early_eaten is non-zero.

This behavior causes a stall when the current message occupies the very
tail end of a massive skb, and strp_peek/need_bytes indicates that the
remainder of the current message has yet to arrive on the socket. The
TCP receive buffer is totally full, causing the TCP window to go to
zero, so the remainder of the message will never arrive.

Incrementing the value returned by __strp_recv by the amount otherwise
stored in early_eaten prevents stalls of this nature.

Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-28 21:37:26 +09:00
Vakul Garg
456488cd95 strparser: Don't schedule in workqueue in paused state
In function strp_data_ready(), it is useless to call queue_work if
the state of strparser is already paused. The state checking should
be done before calling queue_work. The change reduces the context
switches and improves the ktls-rx throughput by approx 20% (measured
on cortex-a53 based platform).

Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Acked-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-21 09:54:05 +09:00
Doron Roberts-Kedes
7170e6045a strparser: Add __strp_unpause and use it in ktls.
strp_unpause queues strp_work in order to parse any messages that
arrived while the strparser was paused. However, the process invoking
strp_unpause could eagerly parse a buffered message itself if it held
the sock lock.

__strp_unpause is an alternative to strp_pause that avoids the scheduling
overhead that results when a receiving thread unpauses the strparser
and waits for the next message to be delivered by the workqueue thread.

This patch more than doubled the IOPS achieved in a benchmark of NBD
traffic encrypted using ktls.

Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-06-06 14:07:53 -04:00
Doron Roberts-Kedes
7c5aba211d strparser: Do not call mod_delayed_work with a timeout of LONG_MAX
struct sock's sk_rcvtimeo is initialized to
LONG_MAX/MAX_SCHEDULE_TIMEOUT in sock_init_data. Calling
mod_delayed_work with a timeout of LONG_MAX causes spurious execution of
the work function. timer->expires is set equal to jiffies + LONG_MAX.
When timer_base->clk falls behind the current value of jiffies,
the delta between timer_base->clk and jiffies + LONG_MAX causes the
expiration to be in the past. Returning early from strp_start_timer if
timeo == LONG_MAX solves this problem.

Found while testing net/tls_sw recv path.

Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Reviewed-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-22 21:09:16 -04:00
Doron Roberts-Kedes
9d0c75bf6e strparser: Fix incorrect strp->need_bytes value.
strp_data_ready resets strp->need_bytes to 0 if strp_peek_len indicates
that the remainder of the message has been received. However,
do_strp_work does not reset strp->need_bytes to 0. If do_strp_work
completes a partial message, the value of strp->need_bytes will continue
to reflect the needed bytes of the previous message, causing
future invocations of strp_data_ready to return early if
strp->need_bytes is less than strp_peek_len. Resetting strp->need_bytes
to 0 in __strp_recv on handing a full message to the upper layer solves
this problem.

__strp_recv also calculates strp->need_bytes using stm->accum_len before
stm->accum_len has been incremented by cand_len. This can cause
strp->need_bytes to be equal to the full length of the message instead
of the full length minus the accumulated length. This, in turn, causes
strp_data_ready to return early, even when there is sufficient data to
complete the partial message. Incrementing stm->accum_len before using
it to calculate strp->need_bytes solves this problem.

Found while testing net/tls_sw recv path.

Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Signed-off-by: Doron Roberts-Kedes <doronrk@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-12 21:54:59 -04:00
Dave Watson
cd00edc179 strparser: Fix sign of err codes
strp_parser_err is called with a negative code everywhere, which then
calls abort_parser with a negative code.  strp_msg_timeout calls
abort_parser directly with a positive code.  Negate ETIMEDOUT
to match signed-ness of other calls.

The default abort_parser callback, strp_abort_strp, sets
sk->sk_err to err.  Also negate the error here so sk_err always
holds a positive value, as the rest of the net code expects.  Currently
a negative sk_err can result in endless loops, or user code that
thinks it actually sent/received err bytes.

Found while testing net/tls_sw recv path.

Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Signed-off-by: Dave Watson <davejwatson@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-27 11:00:18 -04:00
Tom Herbert
d66fa9ec53 strparser: Call sock_owned_by_user_nocheck
strparser wants to check socket ownership without producing any
warnings. As indicated by the comment in the code, it is permissible
for owned_by_user to return true.

Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Reported-by: syzbot <syzkaller@googlegroups.com>
Reported-and-tested-by: <syzbot+c91c53af67f9ebe599a337d2e70950366153b295@syzkaller.appspotmail.com>
Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-12-28 14:28:22 -05:00
Tom Herbert
829385f08a strparser: Use delayed work instead of timer for msg timeout
Sock lock may be taken in the message timer function which is a
problem since timers run in BH. Instead of timers use delayed_work.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: bbb03029a8 ("strparser: Generalize strparser")
Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-10-25 10:37:11 +09:00
Eric Biggers
3fd8712707 strparser: initialize all callbacks
commit bbb03029a8 ("strparser: Generalize strparser") added more
function pointers to 'struct strp_callbacks'; however, kcm_attach() was
not updated to initialize them.  This could cause the ->lock() and/or
->unlock() function pointers to be set to garbage values, causing a
crash in strp_work().

Fix the bug by moving the callback structs into static memory, so
unspecified members are zeroed.  Also constify them while we're at it.

This bug was found by syzkaller, which encountered the following splat:

    IP: 0x55
    PGD 3b1ca067
    P4D 3b1ca067
    PUD 3b12f067
    PMD 0

    Oops: 0010 [#1] SMP KASAN
    Dumping ftrace buffer:
       (ftrace buffer empty)
    Modules linked in:
    CPU: 2 PID: 1194 Comm: kworker/u8:1 Not tainted 4.13.0-rc4-next-20170811 #2
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
    Workqueue: kstrp strp_work
    task: ffff88006bb0e480 task.stack: ffff88006bb10000
    RIP: 0010:0x55
    RSP: 0018:ffff88006bb17540 EFLAGS: 00010246
    RAX: dffffc0000000000 RBX: ffff88006ce4bd60 RCX: 0000000000000000
    RDX: 1ffff1000d9c97bd RSI: 0000000000000000 RDI: ffff88006ce4bc48
    RBP: ffff88006bb17558 R08: ffffffff81467ab2 R09: 0000000000000000
    R10: ffff88006bb17438 R11: ffff88006bb17940 R12: ffff88006ce4bc48
    R13: ffff88003c683018 R14: ffff88006bb17980 R15: ffff88003c683000
    FS:  0000000000000000(0000) GS:ffff88006de00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000000055 CR3: 000000003c145000 CR4: 00000000000006e0
    DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
    Call Trace:
     process_one_work+0xbf3/0x1bc0 kernel/workqueue.c:2098
     worker_thread+0x223/0x1860 kernel/workqueue.c:2233
     kthread+0x35e/0x430 kernel/kthread.c:231
     ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
    Code:  Bad RIP value.
    RIP: 0x55 RSP: ffff88006bb17540
    CR2: 0000000000000055
    ---[ end trace f0e4920047069cee ]---

Here is a C reproducer (requires CONFIG_BPF_SYSCALL=y and
CONFIG_AF_KCM=y):

    #include <linux/bpf.h>
    #include <linux/kcm.h>
    #include <linux/types.h>
    #include <stdint.h>
    #include <sys/ioctl.h>
    #include <sys/socket.h>
    #include <sys/syscall.h>
    #include <unistd.h>

    static const struct bpf_insn bpf_insns[3] = {
        { .code = 0xb7 }, /* BPF_MOV64_IMM(0, 0) */
        { .code = 0x95 }, /* BPF_EXIT_INSN() */
    };

    static const union bpf_attr bpf_attr = {
        .prog_type = 1,
        .insn_cnt = 2,
        .insns = (uintptr_t)&bpf_insns,
        .license = (uintptr_t)"",
    };

    int main(void)
    {
        int bpf_fd = syscall(__NR_bpf, BPF_PROG_LOAD,
                             &bpf_attr, sizeof(bpf_attr));
        int inet_fd = socket(AF_INET, SOCK_STREAM, 0);
        int kcm_fd = socket(AF_KCM, SOCK_DGRAM, 0);

        ioctl(kcm_fd, SIOCKCMATTACH,
              &(struct kcm_attach) { .fd = inet_fd, .bpf_fd = bpf_fd });
    }

Fixes: bbb03029a8 ("strparser: Generalize strparser")
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Tom Herbert <tom@quantonium.net>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-24 21:57:50 -07:00
John Fastabend
f26de110f4 net: early init support for strparser
It is useful to allow strparser to init sockets before the read_sock
callback has been established.

Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-16 11:27:52 -07:00
Tom Herbert
bbb03029a8 strparser: Generalize strparser
Generalize strparser from more than just being used in conjunction
with read_sock. strparser will also be used in the send path with
zero proxy. The primary change is to create strp_process function
that performs the critical processing on skbs. The documentation
is also updated to reflect the new uses.

Signed-off-by: Tom Herbert <tom@quantonium.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-01 15:26:19 -07:00
WANG Cong
f78ef7cd9a strparser: destroy workqueue on module exit
Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Cc: Tom Herbert <tom@herbertland.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-03-03 20:43:26 -08:00
Geert Uytterhoeven
6d3a4c4046 strparser: Propagate correct error code in strp_recv()
With m68k-linux-gnu-gcc-4.1:

    net/strparser/strparser.c: In function ‘strp_recv’:
    net/strparser/strparser.c:98: warning: ‘err’ may be used uninitialized in this function

Pass "len" (which is an error code when negative) instead of the
uninitialized "err" variable to fix this.

Fixes: 43a0c6751a ("strparser: Stream parser for messages")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-10-12 01:51:49 -04:00
Tom Herbert
96a5908347 kcm: Remove TCP specific references from kcm and strparser
kcm and strparser need to work with any type of stream socket not just
TCP. Eliminate references to TCP and call generic proto_ops functions of
read_sock and peek_len. Also in strp_init check if the socket support
the proto_ops read_sock and peek_len.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-28 23:32:41 -04:00
Tom Herbert
cff6a334e6 strparser: Queue work when being unpaused
When the upper layer unpauses a stream parser connection we need to
queue rx_work to make sure no events are missed.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-23 16:23:12 -07:00
Dave Watson
a01512dbe3 net: strparser: fix strparser sk_user_data check
sk_user_data mismatch between what kcm expects (psock) and what strparser expects (strparser).

Queued rx_work, for example calling strp_check_rcv after socket buffer changes, will never complete.

sk_user_data is unused in strparser, so just remove the check.

Signed-off-by: Dave Watson <davejwatson@fb.com>
Acked-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-22 22:43:16 -07:00
Tom Herbert
43a0c6751a strparser: Stream parser for messages
This patch introduces a utility for parsing application layer protocol
messages in a TCP stream. This is a generalization of the mechanism
implemented of Kernel Connection Multiplexor.

The API includes a context structure, a set of callbacks, utility
functions, and a data ready function.

A stream parser instance is defined by a strparse structure that
is bound to a TCP socket. The function to initialize the structure
is:

int strp_init(struct strparser *strp, struct sock *csk,
              struct strp_callbacks *cb);

csk is the TCP socket being bound to and cb are the parser callbacks.

The upper layer calls strp_tcp_data_ready when data is ready on the lower
socket for strparser to process. This should be called from a data_ready
callback that is set on the socket:

void strp_tcp_data_ready(struct strparser *strp);

A parser is bound to a TCP socket by setting data_ready function to
strp_tcp_data_ready so that all receive indications on the socket
go through the parser. This is assumes that sk_user_data is set to
the strparser structure.

There are four callbacks.
 - parse_msg is called to parse the message (returns length or error).
 - rcv_msg is called when a complete message has been received
 - read_sock_done is called when data_ready function exits
 - abort_parser is called to abort the parser

The input to parse_msg is an skbuff which contains next message under
construction. The backend processing of parse_msg will parse the
application layer protocol headers to determine the length of
the message in the stream. The possible return values are:

   >0 : indicates length of successfully parsed message
   0  : indicates more data must be received to parse the message
   -ESTRPIPE : current message should not be processed by the
      kernel, return control of the socket to userspace which
      can proceed to read the messages itself
   other < 0 : Error is parsing, give control back to userspace
      assuming that synchronzation is lost and the stream
      is unrecoverable (application expected to close TCP socket)

In the case of error return (< 0) strparse will stop the parser
and report and error to userspace. The application must deal
with the error. To handle the error the strparser is unbound
from the TCP socket. If the error indicates that the stream
TCP socket is at recoverable point (ESTRPIPE) then the application
can read the TCP socket to process the stream. Once the application
has dealt with the exceptions in the stream, it may again bind the
socket to a strparser to continue data operations.

Note that ENODATA may be returned to the application. In this case
parse_msg returned -ESTRPIPE, however strparser was unable to maintain
synchronization of the stream (i.e. some of the message in question
was already read by the parser).

strp_pause and strp_unpause are used to provide flow control. For
instance, if rcv_msg is called but the upper layer can't immediately
consume the message it can hold the message and pause strparser.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-17 19:36:23 -04:00